It sounds like you are experiencing a tremor. Tremors can be brought out by fatigue and stress, or might be exacerbated by taking in a lot of stimulants, such as caffeine from coffee or soda. You may want to try getting a bit more sleep and cut out caffeine for a little while and see if that makes a difference.
If the tremor persists with these methods, you may have an essential tremor. This is a mild neurological disorder of unknown cause in which a tremor (usually of the upper extremities) that is worse with action and better at rest. Essential tremor is also made worse by caffeine, fatigue, and stress. Alcohol, on the other hand, usually makes essential tremor better.
There are also a few more neurological conditions that could cause tremor. These would be very rare in someone your age, however if the tremor is persisting, you should go see your primary care doctor
or a neurologist
. They will be able to perform a complete neurological examination to make sure you do not have any concerning neurological symptoms. If they diagnose you with essential tremor, they will also be able to suggest medications to help keep the tremor symptoms under control.